Which chemical reaction produces ortho-hydroxybenzoic acid, the primary reaction product used as a raw material for medications?
Solution:
The correct answer is Kolbe’s reaction (Kolbe–Schmitt reaction).
Explanation:
Ortho-hydroxybenzoic acid (salicylic acid) is prepared by heating sodium phenoxide with carbon dioxide (CO₂) under pressure (about 4–7 atm) at around 400 K. The intermediate formed is sodium salicylate, which on acidification gives salicylic acid.
C₆H₅ONa + CO₂ → C₆H₄(OH)COONa →(H⁺)→ C₆H₄(OH)COOH
Importance:
Salicylic acid is an important compound used in the manufacture of several medicines:
- Aspirin (acetylsalicylic acid): Used as a pain reliever, fever reducer, and anti-inflammatory drug
- Methyl salicylate: Used in topical ointments for muscle pain relief
Why other options are incorrect:
- Reimer–Tiemann reaction: Produces salicylaldehyde (–CHO group), not salicylic acid (–COOH group)
- Stephen reaction: Used to prepare aldehydes from nitriles
- Friedel–Crafts reaction: Used for alkylation or acylation of aromatic rings, not for forming hydroxy acids
Correct Answer: Kolbe’s reaction
Important Questions from Chemical Reaction
An iron nail dipped in copper sulphate solution turns brown. This is due to which one of the following types of reactions?
Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour?
Airbags work on the principle of a chemical reaction triggered by the impact producing a gaseous product that causes a sudden volume change. Which one among the following chemical conversions is responsible for this?
Which one of the following is the correct reactivity series with water?
Silver artefacts get tarnished in air due to the formation of
